Image-Guided Rx

Image Guided Techniques

Key Points

  • Image-guided treatment of leiomyomas refers to uterine sparing procedures where treatment is performed under fluoroscopic, ultrasound, or magnetic resonance imaging.
  • There are two basic categories of image-guided therapy; one is transient devascularization (uterine artery embolization, or UAE) usually performed by interventional radiologists under fluoroscopic guidance, while the others are targeted hyperthermic ablation techniques  using radiofrequency, microwave, or focused high frequency ultrasound energy.
  • While they are uterine sparing requiring no incisions, the utility of these procedures for those with infertility or desires for future pregnancies has yet to be clearly defined.

There exist several techniques whereby imaging can be used to used to direct therapy for leiomyomas. While the original such approach was occlusion of the uterine arteries with embolic materal - uterine artery embolization (UAE) - in subsequent years, hyperthermia generated by focused ultrasound, microwaves, and radiofrequency (RF) electrical energy have been introduced throughout the first part of the 21st century. Most of the techniques have been evaluated and/or approved for symptoms like abnormal uterine bleeding and pressure.  However, their role in women with infertility or who desire fertility in the future is unclear. As a result,  myomectomy is the procedure best investigated for the treatment of fertility, or when future fertility is desired. Determining which of these methods is most appropriate for a given patient is a process informed by the available techniques, and to the leiomyoma phenotype of the given patient. In general, women for whom hysteroscopic myomectomy is feasible are best treated surgically.

Uterine Artery Occlusion/Embolization

Also known as uterine artery occlusion, or sometimes as "uterine fibroid embolization", UAE really refers to blockage of both uterine arteries, usually by materials positioned under radiologically directed fluoroscopic imaging. A catheter is passed through the right femoral artery just below the inguinal ligament usually with the patient under conscious sedation. For UAE,  -he radiologist then directs the catheter sequentially into each uterine artery and deposits a solution comprising tiny spheres until they collectively block the blood flow in the artery. The resulting ischemia is temporary, several hours - but generally enough to cause ischemic necrosis in the fibroids. The myometrium is more resistant to the lack of blood flow, and collateral vascularization rescues the uterus in the ensuing hours and days.  Uterine artery occlusion can also be performed via an abdominal approach, either laparoscopic or laparotomic, and, while usually used with temporary means (eg removable clips) as an adjunct to myomectomy, has also been reported as an isolated and permanent procedure with outcomes similar to UAE.

High Frequency Ultrasound (HIFU)

More on HIFU

By using a parabolic mirror ultrasonic energy can be focused on the leiomyomas thereby raising the temperature to the point of coagulative necrosis. The ultrasound is directed under the guidance of either ultrasound or MRI.  Published success rates are relatively high for abnormal bleeding symptoms or for reduction in leiomyoma or uterine volume.  The role in women with infertility or desiring future fertility is not clear.

Radiofrequency Ablation (RFA)

More on RFA

Radiofrequency electricity is used in most surgical procedures to seal blood vessels by the processes of coagulation and desiccation. For fibroids, electrodes with multiple tines are directed into the fibroid under ultrasound direction either applied under laparoscopic, vaginal, or intrauterine ultrasound guidance - radiofrequency ablation (RFA). With activation of the RF generator, either thermal or impedance measurement provides feedback to the surgeon to determine the end point of the procedure. 

Microwave Ablation

Microwave energy can be used to ablate leiomyomas by positioning narrow-gage "antennae" transcutaneously into the tumors under ultrasound guidance. This approach is available in only selected countries and communities so won't be an option for many patients.

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